Subject: Re: linux-next: build failure after merge of the mm-hotfixes tree

From: Stephen Rothwell <[email-masked]>
Date: Thu, 29 May 2025 10:03:17 +1000

Hi all,

On Thu, 29 May 2025 09:59:38 +1000 Stephen Rothwell <[email-masked]> wrote:

> 
> After merging the mm-hotfixes tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
> 
> mm/khugepaged.c: In function 'hpage_collapse_scan_file':
> mm/khugepaged.c:2337:21: error: implicit declaration of function 'folio_expected_ref_count' [-Wimplicit-function-declaration]
>  2337 |                 if (folio_expected_ref_count(folio) + 1 != folio_ref_count(folio)) {
>       |                     ^~~~~~~~~~~~~~~~~~~~~~~~
> 
> Caused by commit
> 
>   3bdddbba5f02 ("mm/khugepaged: fix race with folio split/free using temporary reference")
> 
> I have reverted that commit for today.

folio_expected_ref_count() is not introduced until commit

  86ebd50224c0 ("mm: add folio_expected_ref_count() for reference count calculation")

in the mm-stable tree.

-- 
Cheers,
Stephen Rothwell